Subframe construction is known for mounting an engine, suspensions and the like by partly mounting subframes to a vehicle body. Subframes are used in an area where enormous external force is exerted on a vehicle body, such as an engine-mounting space, suspension-mounting space and the like. Subframes are usually mounted at the bottom of a vehicle body at the front and the rear, respectively. For example in a front engine rear drive type vehicle, front suspensions and an engine are mounted on a front subframe at the front side of the vehicle body, and rear suspensions and a differential gear unit are mounted on a rear subframe at the rear side of the vehicle body.
As mentioned above, these subframes are used in an area where enormous external force is exerted. However, such external force is exerted on a connecting part between the subframe and the vehicle body as well. For this reason, construction for mounting a subframe is a very important factor for the design of a vehicle body. It is also necessary to ensure layout free structure since various equipment are mounted on a subframe. A subframe is often mounted to a subframe mounting surface of a vehicle body at inclined angles.
FIG. 6 shows a conventional construction for mounting a subframe to a vehicle body, in which FIG. 6A shows a mounting construction by the use of a bracket, and FIG. 6B shows a mounting construction by the use of a collar.
As shown in FIG. 6A, a bracket 53 provided with a bolt insertion hole and a pipe insertion sleeve is fitted onto one end of a pipe constructing a subframe and thereafter welded We. The subframe (pipe 51) is then mounted to a vehicle body 55 in such a way that the bracket 53 is fixed to the vehicle body 55 by a bolt 54. Meanwhile, as shown in FIG. 6B, a pipe 51 constructing a subframe is provided with an insertion hole. A hollow collar 52 is inserted into the insertion hole and thereafter welded We. The subframe (pipe 51) is then mounted to the vehicle body 55 by the insertion of a bolt 54 through the collar 52.
However, in the mounting construction shown in FIG. 6A, there is a space restriction since the bracket 53 is connected at the end of the pipe 51. The bracket 53 may be connected at an intermediate portion of the pipes 51. However, extensive mounting space is required. In either case, such a mounting construction is not preferable due to restriction of the layout space. The mounting construction shown in FIG. 6A also has a problem in its strength.
Meanwhile, the mounting construction provided with an insertion hole through the pipe 51 (FIG. 6B) is free from restriction of the layout space. However, since the subframe contacts to the vehicle body 55 merely at the collar 52 inserted through the pipe 51, contact area and contact width to the vehicle body become smaller, leading to insufficient mounting strength of the mounting construction against external force to be applied. Further, in the case that the subframe (pipe 51) is mounted to a subframe mounting surface 55a of the vehicle body 55 at inclined angles, the distance between the subframe mounting surface 55a and the center axis of a material constructing a subframe (pipe 51) becomes greater. This leads to decreased mounting strength as well as inaccurate positioning of the subframe.
Moreover, if the welded portion (weld We) of the bracket 53 or the collar 52 to the pipe 51 peels off, the subframe (pipe 51) may fall on the ground.
Further, the mounting construction should not be complicated in its structure in order to ensure simple manufacture and reduced cost.
In view of the above, the present invention seeks to provide a construction for mounting a subframe to a vehicle body, which ensures superior mounting strength and less mounting space requirement, and which facilitates inclined mounting of the subframe to the vehicle body.